Liquid type electrophotography developing apparatus

ABSTRACT

Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, the apparatus including (1) means for containing a liquid developer; (2) a plurality of developing electrodes, each of which is at least partially disposed within the liquid developer; (3) means for moving each of the developing electrodes along a closed path; (4) means for intermittently feeding the web of electrophotographic sensitive material through the developing liquid after each image exposure of the web to develop latent images on the sensitive material corresponding to the exposure images; (5) means for substantially maintaining a predetermined spacing between the sensitive material and the developing electrodes while the sensitive material is in the liquid developer; and the developing electrodes being so positioned that said images on the web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever the web is stopped in the developer liquid during the intermittent feeding thereof so that the latent images are uniformly developed when the web is stopped.

United States Patent Fukushima et al.

[ 1 LIQUID TYPE ELECTROPHOTOGRAPI-IY DEVELOPING APPARATUS [7 2] Inventors: Osamu Fukushima; Masamichi Sato; Seiii Matsumoto, all of Asaka, Japan [73] Assignee: Fuji Photo Film Co., Ltd.,

' Kanagawa, Japan [22] Filed: Sept. 25, 1970 [21] Appl. No.: 75,491

[30] Foreign Application Priority Data- Sept. 26, 1969 Japan ..44/76682 [S2] U.S. Cl ..ll8/637, 117/37 LE, ll8/DIG. 23 [51] Int. Cl. ..G03g 13/00 [58] Field ofSearch....118/637, 637 LX; 117/37 LX;

[56] References Cited UNITED STATES PATENTS 7 3,227,549 1/1966 Ullrich, Jr. et al ..117/37 LE 3,601,092 8/1971 Toyokazu ..l18/637 3,577,259 5/1971 Masamichi Sato ..l18/637 3,556,050 l/l97l Trachtenberg et al. 18/637 3,186,326 6/1965 Schmidt ..95/94 3,249,088 5/1966 Ostensen ..1 18/637 3,384,051 5/1968 I-Iunstiger ..l18/637 3,128,683 4/1964 Rubin ..118/637 FOREIGN PATENTS OR APPLICATIONS 938,349 1011963 GreatBritain ..117/37 LX 1 Dec. 26, 1972 Primary Examiner-Mervin Stein Assistant Examiner-Leo Millstein Attorney-Gerald J. Ferguson, Jr.

[57 ABSTRACT Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially. exposed along the length of a web of electrophotographic sensitive material, the apparatus including (1) means for containing a liquid developer; (2) a plurality of developing electrodes, each of which is at least partially disposed within the liquid developer; (3) means for moving each of the developing electrodes along a closed path; (4) means for intermittently feeding the web of electrophotographic sensitive material through the developing liquid after each image exposure of the web to develop latent images on the sensitive material corresponding to the exposure images; (5) means for substantially maintaining a predetermined spacing between the sensitive material and the developing electrodes while the sensitive material is in the liquid developer; and the developing electrodes being so positioned that said images on the web are respectively in complete faceto-face relationship with respect to said developing electrodes whenever the web is stopped in the developer liquid during the intermittent feeding thereof so that the latent images are uniformly developed when the web is stopped.

9 Claims, 11 Drawing Figures PATENTEU I972 3.707.139

sum 2 or 5 INVENTORB jw 7 RNEY. Q

PATENTED [m 1912 3.707; 139 sum 3 or 5 9527/7 wan/Mara Jaw PATENTEU DEC 26 I972 sum u or 5 LIQUID TYPE ELECTROPIIOTOGRAPI-IY DEVELOPING APPARATUS The present invention relates to a liquid type developing apparatus for developing an electrophotographic photosensitive material of the web form bearing an electrostatic latent image thereon.

In general in the liquid type developing process of the electrophotography, an electrophotographic photosensitive material consisting of an electrophotographic photosensitive layer disposed on a conductive substrate is uniformly charged by means of a Corona discharge or the like first, exposed to an image light to form an electrostatic latent image thereon, and brought into contact with a developing solution in which colored particles (toner) are dispersed in an insulating liquid so that the charged particles may stick to the latent image to make a visible image thereon.

In the liquid type developing process as described above, there are various problems or troubles specific thereto. The streaks formed in the image is one of the troubles. The streaks are made by the fact that the toners stick to the photosensitive material downstream of the image in the form of a tail of a comet extending from the end of the image. The reason for the formation of the streaks is not clear, but is is known that the size of the streaks is larger when (l) the spacing between the surface of the electrostatic latent image and the developing electrode is made small in order to reduce the edge effect and (2) the relative speed of the electrostatic latent image with the developing liquid is made high. However, in view of the fact that the high speed of processing of the photosensitive material is desired and that the so-called edge effect, the phenomenon. that the edge of a large area to be developed with high density is developed with high density and the other central residual large area is developed with low density, is desired to be reduced as much as possible, the trouble of the streaks is an unsolvable problem.

Another important trouble is uneveness in developed image. In the event that the spacing between the surface of the latent image on the photosensitive material and the developing electrode used for reducing the edge effect is partly varied, the photosensitive material bearing the latent image is unevenly developed. The closer the developing electrode is located to the electrostatic latent image so as to faithfully develop the image according to the latent image, the more unevenly developed is the latent image.

Under the above disposition of the conventional liquid type developing process in the electrophotography, it has been desired that a novel or improved developing apparatus of the liquid type in which the edge effect is reduced and the streaks and uneveness in developing are as well reduced should be developed.

It is therefore the principal object of the present invention to provide a liquid type electrophotographic developing apparatus in which the edge effect is reduced and the streaks and uneveness in the developed image are as well reduced.

Another object of the present invention is to provide a liquid type electrophotography developing apparatus for developing a web like electrophotographic material with efficiency.

Still another object of the present invention is to provide a liquid type electrophotographic developing apparatus which is provided with a developing electrode and in which the uneveness in developed image and streaks formed in the image are eliminated in spite of the provision of the developing electrode.

Other objects and features of the invention will be made apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional elevational view of the electrophotographic apparatus equipped with the electrophotographic developing apparatus in accordance with the present invention.

FIG. 2 is a cross-sectional elevational view of the electrophotographic apparatus equipped with another embodiment of the developing apparatus in accordance with the present invention.

FIG. 3 is a cross-sectional elevational view of the electrophotographic apparatus equipped with still another embodiment of the developing apparatus in accordance with the present invention.

- FIG. 4 is a perspective view of the developing drum used in the developing apparatus in accordance with the present invention in relation with the photosensitive paper fed therealong.

FIG. 5 is a perspective view of the photosensitive paper guide roller employed in the developing apparatus in accordance with the present invention.

FIG. 6 is a perspective view of the dancer roller employed in the developing apparatus of the present invention.

FIG. 7 is a perspective view of the dancer roller showing the relation thereof with the photosensitive paper fed therealong.

FIG. 8 is a perspective view of the roller provided with sprockets for regulating the feeding speed and the lateral position of the photosensitive paper running therealong showing the relation thereof with the photosensitive paper having perforations, to be engaged with the sprockets guided therealong.

FIG. 9 is a perspective view of the developing belt showing the relation thereof with the photosensitive paper running therealong.

FIG. 10 is a cross-sectional elevational view of apparatus for maintaining a fixed spacing between the paper and the belt in the embodiment of FIG. 3.

FIG. 11 is a diagram showing the relation of the spacing between the developing electrode and the photosensitive paper to be developed with the allowable maximum relative speed of the running paper with the developing liquid.

Now referring to FIG. 1 showing an embodiment of the electrophotographic developing apparatus in accordance with the present invention incorporated into an electrophotographic apparatus, an electrophotographic photosensitive paper wound in a convolution l is fed out through a pair of pinch rollers 2 and 3 which feed the paper therebetween intermittently. The pinch roller 3 on the photosensitive layer side of the paper is preferred to have a hard and smooth surface such as a stainless roller. The pinch roller 2 on the opposite side of the paper is preferred to be made of such soft and elastic material as rubber. Alternatively, the both pinch rollers 2 and 3 may be made of rubber. A dancer roller 4 is disposed to exert tension on the photosensitive paper. The dancer roller 4 is provided at the opposite ends thereof a pair of flanges and 60 as shown in FIG. 6. The paper is further guided to run along a sprocket roller 6 which feeds the paper intermittently by a prescribed length. The paper is pinched by a pinch roller rotating in contact with the sprocket roller 6. The construction of the sprocket roller 6 is clearly shown in FIG. 8. The construction of the pinch roller 5 is so made that the periphery of the pinch roller 5 may push the paper against the surface of the sprocket roller 6 between the sprockets 802 on the roller 6 or the sprockets 802 may be fitted with the groove provided on the pinch roller 5.

The sprocket roller 6 is provided with a pair of lines of sprockets 802 and 802 on the periphery of the cylindrical portion 801 thereof at the portion in the vicinity of the ends thereof, and provided with an elastic material layer 803 such as of rubber. By the combination of the sprocket roller 6 thus made and the photographic paper having perforations on the opposite sides thereof, the adjustment of the position of the image in the case of superposing print method for making a multi-color printing can be easily and certainly conducted. It is also possible to regulate or control the position of the paper by means of optical adjustment wherein an optical mark is provided on the paper and a mark reading device is provided to read the mark on the paper and control the position of the paper electrically.

The photosensitive paper is further fed under a Corona discharging device 7 for making the paper photosensitive. The Corona discharging device 7 performs discharging operation only during the paper is running thereunder. In the downstream of the corona discharging device 7, a white frame forming device 8 is disposed. The white frame forming device 8 includes an elongated light source 9 and a light shielding member extending from the light source to the surface of the running paper. The paper is exposed at the marginal portion of the image frame thereof by the white frame forming device 8 and provided with a white marginal frame thereby. The image projection is performed on the area surrounded by the white frame forming device 8. The photosensitive paper intermittently fed into this portion is exposed with image light by an optical exposing device provided above the paper. The photosensitive paper under the optical exposing device is supported on a paper support 10. The paper support 10 is provided with holes or grooves thereon so that the paper thereon may be brought into tight contact with the surface thereof to make a good plane thereon by means of suction method. When the paper is to be fed thereon, it is desired to eject air through the holes or grooves to let the paper removed from the surface of the paper support 10 and fed smoothly thereon.

The advancing direction of the paper fed is changed by a roller 11. The roller 11 is made of rubber for instance. Under the roller 11 for changing the advancing direction of the paper, a blade wheel 12 is provided for making a liquid of high resistance be stuck on the back surface of the paper before the paper is brought into contact with the developing solution. The liquid of high resistance 13 in the bath 14 is stuck on the back surface of the paper so that the back surface of the paper may be prevented from stained with the developing solution. The paper running along the roller 11 is sandwiched between the roller 11 and another roller 15.

The roller 15 is made of porous material such as sponge and used for the same purpose as that of the blade wheel 12, that is, the porous roller 15 is used to coat the liquid of high resistance 17 in the bath 18 through another porous roller 16 rotated in contact therewith. The two porous rollers 15 and 16 are connected with each other through a lever 52 and the roller 15 is removed from the paper when the photosensitive paper is fed on. It will be understood that the back surface of the paper also may be coated with the liquid of high resistance by means of a sponge roller like the roller 15.

The rollers 19 through 24 are all used for changing the advancing direction of the paper running in the developing solution. The shape of the rollers 19, 20, 21, 22, 23 and 24 is preferred to be as shown in FIG. 5. As clearly shown in FIG. 5, the roller is provided with a pair of spirals extending outward from the center thereof so that the paper running therealong may not be wrinkled. Such a roller having a surface with spirals may be made either by forming a spiral groove on the surface of a smooth roller of stainless steel or by spirally winding a rubber strip or plastic strip around the stainless steel roller.

The developing drums 27, 28, 29 and 30 are rotatably disposed in the developing solution in parallel with each other and the shape thereof is preferred to be as shown in FIG. 4. The smooth drum surface 401 is machine-worked and serves as a developing electrode in the case that the paper is wound thereon. The developing drums 27, 28, 29 and 30 are provided with a pair of protrusions 402 and 404 on the periphery thereof at the opposite ends thereof. The pair of protrusions 402 and 404 are also provided with a spiral groove thereon as shown in FIG. 5 on the rollers 19 through 24. The photosensitive paper 403 of the web type is strained between the protrusions 402 and 404 above the smooth surface 401 of the developing drum so that a definite spacing is formed between the surface of the developing drum and the surface of the photosensitive paper. Accordingly, the developing drum is rotated with the existence of the developing solution between the surface of the drum and the paper running therealong. The smaller is the spacing between the paper and the developing electrode, the larger is the effect of the drum surface as a developing electrode. However, if the spacing between the paper and the surface of the drum is too narrow, a sufficient developing is not performed clue to the shortage of the developing solution and sometimes the image developed is damaged by the contact of the paper with the surface of the drum. In the embodiment of the developing apparatus shown in FIG. 1, the spacing between the paper and the drum surface is differed in the different developing drum. The spacing is reduced step by step according to the advancing of the developing process. The difference between the diameters at the center of the drum and at the end thereof with the protrusion is reduced from 5 mm at the first developing drum 27 to 0.05 mm at the last developing drum 30. The surface of the developing drums 27, 28, 29 and 30 may be formed ofa metal plate provided with fine holes or of a wire net in order to improve the supply of the developing solution on the surface.

The paper fed intermittently in the exposure process is also fed intermittently in the developing process.

When the paper is stopped, the exposed area of the paper shown with hatch in FIG. 1 is stopped in face-toface relation with the surface of the developing drums 27, 28, 29 and 30 serving as developing electrodes. The rollers 19, 20, 21, 22, 23 and 24 are located at the positions for holding the paper at the unexposed area thereof. Developing solution supplying devices 31, 32, 33 and 34 are located at the upstream of the paper in contact with the developing drum so that the fresh and clean solution is always supplied into the spacing between the paper and the drum. The developing solution container 39 including the above-described rollers and drums is provided at the bottom thereof with an exhaust outlet 37. Between the drums 27 and 30 and the drums 28 and 29, there are provided scraping off means 35 and 36 made of soft member such as flannel, felt and the like. The thin layer of developing solution stuck on the surface of the developing drum is scraped off by the scraping off means when the drum is rotated.

The paper is further guided by the rollers 25, 26 and 47 into a cleaning solution 43 in a bath 45 after developed. The cleaning solution is supplied through the cleaning solution ejecting devices 40, 41 and 42 in or above the bath 45. The used cleaning solution is exhausted through an exhausting outlet 46. The lowest roller 47 in the cleaning solution bath 45 is a dancer roller and is constructed as shown in FIG. 7. The dancer roller 47 is composed of a pair of flange portions 701 and 701 at the opposite ends, a pair of roller portions 702 and 702 extending inwardly from the flanges, and a shaft 703 connecting the roller portions 702 and 702 on the opposite sides thereof. The paper is pulled downward by the dancer roller 47 at the roller portions 702 and 702 thereof.

A pair of squeeze rollers 48 and 49 are provided above the cleaning bath 45 and downstream of the cleaning bath for squeezing out the cleaning solution carried by the paper when the paper is fed out of the solution. The position of the dancer roller 47 is required to be located at the position wherein the exposed area of the paper is never stopped at the level of the solution with a part thereof exposed out of the cleaning solution 43. The position of the squeeze rollers 48 and 49 are so set that the exposed and developed area of the paper may not be stopped at the squeeze rollers 48 and 49 when the paper feed is stopped. In the. embodiment shown in FIG. 1, the squeeze roller 48 is made of an elastic material and the other squeeze roller 49 is made of a metal roller with mirror finishing. The photosensitive paper thus processed is wound on a wind-up roller 51 which winds up the processed paper with a constant torque.

In accordance with the liquid type developing apparatus of the present invention as described above and shown in FIG. 1, the photosensitive paper is intermittently fed through the developing solution and exposed with a constant interval. In order to prevent the uneveness in developing effect at the time of stopping in the intermittent movement of the paper, the exposed area to be developed is in the face-to-face relation with the developing electrode when the paper is stopped. Thus, the exposed area is uniformly effected by the developing electrode. The developing solution between the paper and the developing electrode is always changes with the pure solution and, accordingly, the developing operation can be uniformly and sufficiently performed. Since the paper is developed with the pure solution running therewith on the developing electrode, there is no problem of streaks as set forth above. And since a plurality of developing electrodes are utilized in the developing process, the unevenness in developing effect by the respective developing electrodes is averaged to effect a uniform developing performance.

In FIG. 2 is shown another embodiment of the developing apparatus in accordance with the present invention. In this second embodiment of the apparatus, three developing drums 201, 202 and 203 are arranged in the developingsolution and above the drums three developing solution supplying devices 204, 205 and 206 are disposed to supply developing solution between the paper and the'surface of the drums serving as the developing electrodes. On the respective developing drums 201, 202 and 203 are provided the used developing solution scraping off devices 207, 208 and 209. By this embodiment of the developing apparatus of the present invention, the same results as by the first embodiment thereof shown in FIG. 1 are obtained.

In FIG. 3 is shown still another embodiment of the developing apparatus in accordance with the present invention. In this third embodiment of the present invention, conductive endless belts 301, 302 and 303 are employed instead of the drums 201, 202 and 203 employed in the second embodiment shown in FIG. 2. The endless belts 301, 302 and 303 serving as the developing electrodes are stretched between three pairs of rollers 304 and 307, 305 and 308, and 306 and 309. At least one of the pairs of the rollers are driven to make the endless belts run along the rollers. The combination of the rollers and the endless belt is shown in FIG. 9 in relation with the photosensitive paper running therealong. In FIG. 9, the endless belt 901 is stretched between a roller 902 and a roller 903. The latter roller 903 is provided with the spiral grooves for exerting outwardly effecting tension on the paper running therealong. Since it is difficult to maintain the spacing between the paper and the belt constant in the third embodiment as shown in FIG. 3, an additional construction for keeping the spacing constant is necessitated. As one of the construction, a pair of guide plates 101 and 102 disposed behind the paper and the belt are able to be adopted, see FIG. 10. The paper and the endless belts are pushed against the guide plates and guided by the guide plates by supplying the developing solution into the spacing between the paper and the endless belts with the developing solution supplying devices 310, 311 and 312 disposed on the level of the solution. The effect of the supplied solution for urging the paper and belts onto the guide plates is increased by disposing sucking devices 103 on the guide plates.

In the developing apparatus in accordance with the present invention, the electrostatic latent image is developed with the developing solution carried between the developing electrode and the latent image on the paper. The relation between the allowable maximum speed of the flowing of the developing solution and the spacing between the paper and the surface of the drum serving as a developing electrode is shown in FIG. 11 according to our experiment. The spacing between the paper and the surface of the developing drum is taken on the abcissa and the allowable maximum speed of the flowing of the developing solution is taken on the ordinate. The lower line in the graph shown in FIG. 11 represents the limit at which the streaks of 2.0 reflection density is not seen on the image, and the upper line represents the limit at which the streaks of 1 mm long of 2.0 reflection density is seen on the image, both in the case of one minute developing by the developing solution supplied between the paper and the surface of the drum. Therefore, the zone I is a range wherein no streak is seen and the zone ll is a range wherein a streak of maximum 1 mm is seen. The zone III is a range wherein streaks of longer than 1 mm are seen. Under the condition in the zone II, it is improper to develop an image of continuous gradation. Under the condition in the zone lll, it is difficult to develop even a line image.

It should he therefore understood that the apparatus in accordance with the present invention should be designed to have condition in the range I in the case of developing a continuous gradation image, and have condition in the range ll or 1 in the case of developing a line image.

What is claimed is:

1. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising:

means for containing a liquid developer;

a plurality of developing electrodes, each of which is at least partially disposed within said liquid developer;

means for moving each of said developing electrodes along a closed path;

means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images;

means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and

said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.

2. A liquid type electrophotographic developing apparatus as claimed in claim 6 wherein each said developing electrode is a drum having protrusions on the opposite ends thereof.

3. A liquid type electrophotographic developing apparatus as claimed in claim 2 wherein scraping off means is provided for scraping off the thin layer of developing solution stuck on the drum.

4. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising:

means for containing a liquid developer;

a plurality of developing electrodes, each of which comprises an endless belt stretched between a pair of rollers disposed in the container means and each of which is at least partially disposed within said liquid developer;

means for moving each of said developing electrodes along a closed path;

means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images;

means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and

said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.

5. Liquid developing apparatus as in claim 4 where said means for maintaining a predetermined spacing between each endless belt and said web includes 1. a pair of guide plates between which said web and endless belt are disposed; and

2. means for injecting said developer liquid between said web and said endless belt at approximately the point where they enter into the passage formed by said pair of guide plates so that said web is pushed against one of said guide plates and said endless belt is pushed against the other.

6. Liquid developing apparatus as in claim 5 where said guide plates have openings therein, said guide plates being connected to suction means so that the holding action of said web and said endless belt against their respective guide plates is further facilitated.

7. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising:

means for containing a liquid developer;

a plurality of developing electrodes, each of which is at least partially disposed within said liquid developer;

means for moving each of said developing electrodes along a closed path;

means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images;

means for decreasing spacing between said web and successive developing electrodes while said web is in said liquid developer; and

said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.

8. Liquid developing apparatus as in claim 7 where said spacing between the first of said developing electrodes and said web is mm. and the spacing between the last of said developing electrodes and said web is 0.05 mm.

9. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising:

means for containing a liquid developer;

a plurality of developing electrodes, each of which comprises a drum having protrusions on the opposite ends thereof and openings therein to improve the supply of the liquid developer and each of which is at least partially disposed within said liquid developer;

means for moving each of said developing electrodes along a closed path; '7 means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images; means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped. 

1. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising: means for containing a liquid developer; a plurality of developing electrodes, each of which is at least partially disposed within said liquid developer; means for moving each of said developing electrodes along a closed path; meAns for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images; means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.
 2. A liquid type electrophotographic developing apparatus as claimed in claim 6 wherein each said developing electrode is a drum having protrusions on the opposite ends thereof.
 2. means for injecting said developer liquid between said web and said endless belt at approximately the point where they enter into the passage formed by said pair of guide plates so that said web is pushed against one of said guide plates and said endless belt is pushed against the other.
 3. A liquid type electrophotographic developing apparatus as claimed in claim 2 wherein scraping off means is provided for scraping off the thin layer of developing solution stuck on the drum.
 4. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising: means for containing a liquid developer; a plurality of developing electrodes, each of which comprises an endless belt stretched between a pair of rollers disposed in the container means and each of which is at least partially disposed within said liquid developer; means for moving each of said developing electrodes along a closed path; means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images; means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.
 5. Liquid developing apparatus as in claim 4 where said means for maintaining a predetermined spacing between each endless belt and said web includes
 6. Liquid developing apparatus as in claim 5 where said guide plates have openings therein, said guide plates being connected to suction means so that the holding action of said web and said endless belt against their respective guide plates is further facilitated.
 7. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising: means for containing a liquid developer; a plurality of developing electrodes, each of which is at least partially disposed within said liquid developer; means for moving each of said developing electrodes along a closed path; means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said expoSure images; means for decreasing spacing between said web and successive developing electrodes while said web is in said liquid developer; and said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped.
 8. Liquid developing apparatus as in claim 7 where said spacing between the first of said developing electrodes and said web is 5 mm. and the spacing between the last of said developing electrodes and said web is 0.05 mm.
 9. Liquid developing apparatus for use with an electrophotographic device wherein a plurality of images are sequentially exposed along the length of a web of electrophotographic sensitive material, said apparatus comprising: means for containing a liquid developer; a plurality of developing electrodes, each of which comprises a drum having protrusions on the opposite ends thereof and openings therein to improve the supply of the liquid developer and each of which is at least partially disposed within said liquid developer; means for moving each of said developing electrodes along a closed path; means for intermittently feeding said web of electrophotographic sensitive material through said developing liquid after each image exposure of said web to develop latent images on said sensitive material corresponding to said exposure images; means for substantially maintaining a predetermined spacing between said sensitive material and said developing electrodes while said sensitive material is in said liquid developer; and said developing electrodes being so positioned that said images on said web are respectively in complete face-to-face relationship with respect to said developing electrodes whenever said web is stopped in said developer liquid during the intermittent feeding thereof so that said latent images are uniformly developed when the web is stopped. 